There has been proposed an information recording medium comprised of a photographic film bearing a magnetic layer. For example U.S. Pat. No. 4,947,196 and International Patent Provisional Publication No.90/04254 disclose a roll type photographic film bearing on its backside a magnetic layer containing a magnetic substance for magnetic recording and a photographying camera having a magnetic head. These techniques enable to improve the quality of prints and the efficiency of printing work by inputting to and outputting from the magnetic layer identification information on the light-sensitive material and its manufacturer, information on shooting conditions, information on printing conditions, and information concerning conditions for additional printing.
In these conventional techniques, however, the magnetic layer is made up of a single layer; therefore, every information is recorded in pieces in the longitudinal direction on the same plane, without any means to distinguish significance of information. To users (consumers in general), for example, the dates, places, and purposes (motives) of shooting are constantly important information, while manufacturer information such as that on film identification or printing conditions is no longer necessary once the film is developed to form images.
Accordingly, there are demanded such magnetic layers as are capable of retaining significant information permanently erasing disused information easily.